Britain's spy chiefs are to be scrutinised in public for the first time in a
televised hearing to be held within the next two months.

MPs and peers will question the spending and operations of MI5, MI6 and GCHQ in a session lasting up to two hours.

The hearing could give unprecedented insight into the workings of the most secretive state organisations, as well as a deeper understanding of the nature and severity of terrorist threats facing the country.

Although the date has yet to be agreed, the meeting is to take place before Parliament breaks up for its summer recess in July.

Sir Malcolm Rifkind, the chairman of the intelligence and security committee (ISC), which will hold the hearing, said the sessions aim to ensure the agencies spend public money and use their special legal privileges wisely.

He said: “These are organisations that spend up to £2billion a year of public funds and the public has the right to ask for evidence that there is value for money here.

"These agencies also have legal powers to do things that very few people could do without ending up in the courts: intercepting phone calls, entering premises and so forth. It is right that the agencies are shown to be using these powers appropriately.”

Other ISC representatives will include Sir Menzies Campbell, the former Liberal Democrat leader, Lord Butler of Brockwell, a former cabinet secretary, and Hazel Blears, a former Labour cabinet minister and one-time party chairman.

They will question Andrew Parker, who was appointed head of MI5 five weeks ago, Sir Iain Lobban, who leads GCHQ, and Sir John Sawers, the head of MI6, on a range of issues, although it is unlikely that there will be detailed questions on ongoing operations as they could jeopardise the agencies’ operatives.

Until recently the heads of the intelligence agencies had no public profile, although Sir John, and Sir Jonathan Evans, the former head of MI5, have given occasional speeches on their work.